Contents

Secure SharedPreferences

Introduction

Shared Preferences are key-value based XML files. It is located under /data/data/package_name/shared_prefs/<filename.xml>.

So a user with root privileges can navigate to this location and can change its values. If you want to protect values in your shared preferences, you can write a simple encryption and decryption mechanism.

You should know tough, that Shared Preferences were never built to be secure, it's just a simple way to persist data.

Syntax

public static String encrypt(String input);

public static String decrypt(String input);

Parameters

Parameter

Definition

input

String value to encrypt or decrypt.

Remarks

Shared Preferences were never built to be secure, it's just a simple way to persist data.

It is not a good idea to use shared preferences for storing critical information such as user credentials. To save user credentials (such as passwords) you need to use other methods such as Android's AccountManager.

Securing a Shared Preference

Simple Codec

Here to illustrate the working principle we can use simple encryption and decryption as follows.